Various problems present themselves in design of current inkjet printers, Modern inkjet printers print at very high resolution, for example, 600 or even 1200 dots-per-inch (DPI). As resolution increases, droplet size typically decreases. With increased resolution and decreased dot size. it becomes more important that the pens be precisely located in the carriage. To accomplish accurate positioning of the pen in the carriage, the pen typically has a set of physical X, Y, and Z datums that are seated against a corresponding set of datums in the carriage stall.
Modern inkjet printers typically print in color and have a plurality of color pens. usually printing in cyan, magenta yellow, and black It is often desirable to provide a different pen for each color, so that if a single pen goes bad, only that pen need be replaced. However, each pen must be precisely aligned with the other colors, or the print quality of the printed images will be degraded. Therefore, the system must not only accommodate precision placement of the pens in the stalls, but precise alignment among the colors.
In addition to the mechanical positioning of the pens within the carriage, the pens must be fluidically connected to trailing tubes. The pens usually interface with some type of valve on the ends of the tubes. The pens make connection with these valves when they are inserted into the carriage stall. However, if the pen and valve interface is not correctly designed, the forces exerted on the pen during fluid interconnection will counteract the precision positioning of the datums, resulting in the pens being misaligned. The fluid interconnection mechanism must be designed so as to not act against the precise positioning resulting from the interaction of the datums.
Recent advances in printhead construction have allowed printheads to be designed to be a permanent or semi-permanent part of the printer, with separate ink cartridges that are fluidically connected in some fashion to the printhead
Although the pens are preferably a permanent fixture in the printer, rather than being disposable, it is likely that many such pens will fail before the end of the life of the printer. Therefore, some provision must be made so that the pen can be removed and replaced with a new one. The mechanical datum system and fluid interconnect must also allow the new pen to be reliably and precisely positioned during such replacement. The system would be preferably designed so that installation and subsequent replacements could be done by a purchaser or by a field repair person away from factory conditions.
The invention provides an inkjet printing mechanism designed to receive an ink jet pen having a needle and a shroud surrounding the needle, the shroud attached to the pen by means of a neck, the pen also having pen datums configured for positioning the pen within a printer carriage. The printer includes a printer chassis and a media movement mechanism mounted to the chassis and constructed to position a print medium in a print zone. A carriage is mounted to the chassis and is constructed to receive the pen and to position the pen over the print zone. The carriage has a notch configured to receive the neck when the stall receives the pen. A valve is movably attached to the carriage and is configured to move with respect to the carriage to be received by the shroud when the notch receives the neck. A septum is positioned on the valve and configured such that when the valve is received by the shroud. the septum is pierced by the needle. A set of carriage datums is formed in the stall and configured to interface with the pen datums. A latching mechanism is associated with the carriage and constructed to seat the pen datums against the carriage datums to finely position the pen with respect to the carriage.
The invention also provides a method of installing an inkjet pen into a carriage of an inkjet printing mechanism. The method includes the steps of: placing the pen in a stall of the carriage to guide a neck on the pen into a notch formed in the carriage; moving the pen further into the stall and, by means of registration of the pen with walls of the pen stall, guiding a shroud on the pen over a valve; urging the pen further into the stall until pen datums formed on the pen come into contact with carriage datums formed in the stall; and seating the pen datums again carriage datums to finely position the pen within the carnage;
The invention thus provides for reliable insertion of inkjet pens within their respective carriage stalls. With successive guiding mechanisms for aligning various parts of the pen with corresponding parts of the carriage. The invention allows for installation or replacements of pens to be reliably and easily done by a purchaser or by a field repair person away from factory conditions.
A datum arrangement on the replaceable semi-permanent compact print cartridge includes three x-datums, one y-datum and two z-datums to assure proper seating of the print cartridge in the carriage as well as proper electric and fluidic interconnections.